An Iron(III) Superoxide Corrole from Iron(II) and Dioxygen

Sacramento, Jireh Joy D.; Albert, Therese; Siegler, Maxime A.; Moënne‐Loccoz, Pierre; Goldberg, David

doi:10.1002/anie.202111492

Cited by 12 publications

(3 citation statements)

References 65 publications

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“…Metal-dioxygen species are crucial intermediates in the O 2 activation cycle of metalloenzymes, and their redox reactivities are modulated by the nature of metal ions and ligands in metalloenzymes [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. In living organisms, the metalloporphyrin sites are surrounded by the protein superstructure, which is conducive to avoiding the involvement of metalloporphyrin active sites in unwanted side reactions [ 13 , 15 , 27 , 28 , 29 , 30 ]. However, the complexity of the surrounding protein superstructure restricts access to the metalloporphyrin active sites, resulting in the big challenge in studying the intermediates in O 2 activation by metalloenzymes.…”

Section: Introductionmentioning

confidence: 99%

Isolating Fe-O2 Intermediates in Dioxygen Activation by Iron Porphyrin Complexes

2022

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Dioxygen (O2) is an environmentally benign and abundant oxidant whose utilization is of great interest in the design of bioinspired synthetic catalytic oxidation systems to reduce energy consumption. However, it is unfortunate that utilization of O2 is a significant challenge because of the thermodynamic stability of O2 in its triplet ground state. Nevertheless, nature is able to overcome the spin state barrier using enzymes, which contain transition metals with unpaired d-electrons facilitating the activation of O2 by metal coordination. This inspires bioinorganic chemists to synthesize biomimetic small-molecule iron porphyrin complexes to carry out the O2 activation, wherein Fe-O2 species have been implicated as the key reactive intermediates. In recent years, a number of Fe-O2 intermediates have been synthesized by activating O2 at iron centers supported on porphyrin ligands. In this review, we focus on a few examples of these advances with emphasis in each case on the particular design of iron porphyrin complexes and particular reaction environments to stabilize and isolate metal-O2 intermediates in dioxygen activation, which will provide clues to elucidate structures of reactive intermediates and mechanistic insights in biological processes.

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Section: Introductionmentioning

confidence: 99%

Isolating Fe-O2 Intermediates in Dioxygen Activation by Iron Porphyrin Complexes

2022

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“…The oxygen reduction reaction (ORR) is an essential reaction involved in many natural and artificial energy conversion processes. − Extensive efforts have been made to design and develop new efficient catalysts for ORR and to understand catalyst structural effects on their activities. − On one hand, these efforts lead to the identification of a large number of metal complexes, including those of Mn, − Fe, − Co, − Ni, , and Cu, − as active catalysts for ORR. More importantly, fundamental knowledge to correlate the structure and the catalytic performance of ORR catalysts is learned. ,, For example, it is demonstrated that catalytic ORR activity and selectivity can be improved by introducing functional groups to facilitate electron transfer , and proton transfer , and to provide hydrogen bonding , and electrostatic interactions .…”

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confidence: 99%

Steric Effects on the Oxygen Reduction Reaction with Cobalt Porphyrin Atropisomers

Liu,

Qin,

et al. 2024

ACS Catal.

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The steric effects on the oxygen reduction reaction (ORR) have been rarely studied because O2 is small in size and ORR catalysts with the only difference in steric hindrance are difficult to be designed and synthesized. Herein, we report on homogeneous ORR catalyzed by four Co porphyrin atropisomers in tetrahydrofuran with decamethylferrocene and HClO4 at 298 K. All four atropisomers are active and selective for the 2H+/2e– ORR with an activity order αααα > αααβ > ααββ > αβαβ. Kinetic studies revealed that the four atropisomers have the same ORR mechanism with proton-coupled O2 binding as the rate-determining step.

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“…This largely reduced affinity to external ligands is consistent with the two studies that reported the isolation of iron(II) corroles. [42,43] As nitrophorins have been shown to bind NO in both the Fe(II) and Fe(III) states, [23][24][25][26] our focus turned to the study of its reactions with (1-Fe) 2 . We note that high affinity NO binding has traditionally focused mainly on ferrous model complexes, [11,[26][27][28] not at least because of difficulties of obtaining stable ferric nitrosyl complexes.…”

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confidence: 99%

Reversible Reactions of Nitric Oxide with a Binuclear Iron(III) Nitrophorin Mimic

Sharma,

Saini,

Fridman

et al. 2023

Chemistry A European J

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Construction of functional synthetic systems that can reversibly bind and transport the most biologically important gaseous molecules, oxygen and nitric oxide (NO), remains a contemporary challenge. Myoglobin and nitrophorin perform these respective tasks employing a protein‐embedded heme center where one axial iron site is occupied by a histidine residue and the other is available for small molecule ligation, structural features that are extremely difficult to mimic in protein‐free environments. Indeed, the hitherto reported designs rely on sophisticated multistep syntheses for limiting access to one of the two axial coordination sites in small molecules. We have shown previously that binuclear Ga(III) and Al(III) corroles have available axial sites, and now report a redox‐active binuclear Fe(III) corrole, (1‐Fe)2, in which each (corrolato)Fe(III) center is 5‐coordinate, with one axial site occupied by an imidazole from the other corrole. The binuclear structure is further stabilized by attractive forces between the corrole π systems. Reaction of NO with (1‐Fe)2 affords mononuclear iron nitrosyls, and of functional relevance, the reaction is reversible: nitric oxide is released upon purging the nitrosyls with inert gases, thereby restoring (1‐Fe)2 in solutions or films.

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An Iron(III) Superoxide Corrole from Iron(II) and Dioxygen

Cited by 12 publications

References 65 publications

Isolating Fe-O2 Intermediates in Dioxygen Activation by Iron Porphyrin Complexes

Isolating Fe-O2 Intermediates in Dioxygen Activation by Iron Porphyrin Complexes

Steric Effects on the Oxygen Reduction Reaction with Cobalt Porphyrin Atropisomers

Reversible Reactions of Nitric Oxide with a Binuclear Iron(III) Nitrophorin Mimic

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